I’ve become fascinated by Rolling Ball Sculpture (RBS) and plan to start building my first one soon. Typically a RBS uses a low-voltage, low-RPM motor to carry the marbles to the top of the structure where they begin their journeys down the track. I’ve been scavenging fan and turntable motors from old guitar amps, computers, microwaves, etc., but am at a loss as to how to determine the type of motor (AC v. DC) and operating voltages of these normally-unmarked motors. Thank you in advance for any help you can provide.